Selective heater for container closures



July 16. 1968 E. A. BRAUN SELECTIVE HEATER FOR CONTAINER CLOSURES Filed May 4, 1967 Fl G l 6 Sheets-Sheet 1 INVENTOR y w-u, 9460 ATTORNEY July 16. 1968 7E. A. BRAUN 3,392,458

SELECTIVE HEATER FOR CONTAINER CLOSURES ATTORNEY,

July 16, 1968 E. A. BRAUN 3,392,458

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SELECTIVE HEATER FOR CONTAINER CLOSURES Filed May 4, 1967 6 Sheets-Sheet 5 FIGJO INVE'N TOR [8/6 ,4. 8 640 ATTORNEKS July 16, 1968 E. A. BRAUN 3,392,458

SELECTIVE HEATER FOR CONTAINER CLOSURES Filed May 4, 1967 6 Sheets-Sheet 6 FIG.

fi n \Y\ INVENTOR 39 1 394 Q [em 4. 3071/ Q 40% --$P-386 3y A T TORNEVS United States Patent 3,392,458 SELECTIVE HEATER FOR CONTAINER CLOSURES Eric A. Braun, Farmington, Mich., assignor to Ex-Cell-O Corporation, Detroit, Mich. Filed May 4, 1967, Ser. No. 636,061

Claims. (Cl. 34-105) ABSTRACT OF THE DISCLOSURE A selective heater for container closures having a center hot air distributor formed with triangular pyramid chambers for distributing air to the container corners while preventing heat radiation to adjacent portions of the closure. Elongated slits are used-on the center distributor to selectively distribute heater air to the interior surfaces of the closure while perforated means are used to selectively heat planar outer surfaces of the closure to prevent heat activation of score lines thereon.

' This invention in general relates to paperboard container forming machines and more particularly to an improved selective bottom heater for use in container packaging machines for selective heating of the sealing areas of thermoplastic coated paperboard containers.

At the present time it is common practice in the automatic container packaging machine art to employ containers made from scored paper blanks coated with a heat and pressure sensitive thenmoplastic substance, such as polymer polyethylene. The success of these new containers has caused a great demand for new container forming equipment of the continuous motion type. By this is meant that the containers being formed by the machine are moved through the latter in a continuous procession at a substantially constant rate, the forming operation being carried on while the container blanks are in motion rather than while they are momentarily halted. One machine of this general type is disclosed in U.S. Patent 2,770,175 issued Nov. 13, 1956, in the name of James F. Earp. However, machines of this type were designed for containers that required coating with paraffin or wax after being formed and have no applications to the present plastic coated containers employing foldin bottom closures.

One illustration of a container adapted to be used with the apparatus of the present invention is disclosed in US. Patent No. 3,120,335, issued Feb. 4, 19-64, upon an application of Harry B. Egleston and Charles Z. Monroe, and assigned to the assignee of the instant application. More detailed information on such a container may, or course, be had upon direct reference to such application. For present purposes it will be noted that the container disclosed therein is made of high grade paperboard stock coated on both sides with thermoplastic material such as polyethylene. The polyethylene coating on the paperboard is used not only as a moisture proofing material but also serves as a heat and pressure sensitive adhesive which cooperates in sealing the closure panels of the container so as to make a fluid tight package. A container blank can be formed from the coated paperboard stock in the usual manner of stamping and scoring blanks, folding them over and, by means of a suitable side seam, providing a flattened tube which may be erected into a container in an automatic machine.

A disadvantage of the present paperboard container bottom heaters, such as the one disclosed in US. Patent No. 3,248,841, issued May 3, 1966, upon the application of R. D. Helfelfinger et al., is that they are not completely selective in their operation so as to activate the plastic coating only where essential to thereby assure the moisture proof qualities of the formed closure. Accordingly, it is a primary object of the present invention to provide an improved and efficient bottom heater for use In container packaging machines employing thermoplastic coated paperboard containers, to selectively heat predetermined sealing areas on the bottom closure panels of the containers and prevent the heating of the portrons of the closure subjected to critical stresses and wear.

It is another object of the present invention to provide a novel and improved bottom heater for selective heating of predetermined sealing areas on the bottom closure panels of a thermoplastic coated paperboard contamer which uses a hot air discharge means comprising a plurality of ports disposed in groups to direct hot air at predetermined outer surfaces of the panels and vertical and horizontal slits to direct hot air at predetermined 1nner surfaces of the panels.

It is a further object of the present invention to provide a novel and improved hot air bottom heater for accurate control of the heating of the bottom closure panel sealing areas of a thermoplastic coated paperboard container and which permits the use of lower hot air pressure than has been possible heretofore with prior art hot air heaters.

It is still another object of the present invention to provide a novel and improved method of heating unbroken scored panel areas of the bottom closure panels of a thermoplastic coated paperboard container with the use of a pattern of ports for the application of a predetermined pattern of heat and heating corner scored areas of the bottom closure panels with the use of a pattern of vertical and horizontal slits for the application of a predetermined pattern of heat.

It is still a further object of the present invention to provide a novel and improved hot air heater head for heating the interior of a container closure and which permits the maximum amount of heat dissipation therefrom during its cooling cycle by employing elongated slit openings used as the hot air discharge means.

Other objects, features and advantages of this invention will be apparent from the following detailed description, appended claims, and the accompanying drawings.

In the drawings:

FIG. 1 is a perspective view of an illustrative container fabricating machine embodying the present invention.

FIG. 2 is a layout view of a blank from which the containers are erected and showing the inside surface thereof.

FIG. 3 is the bottom closure portion of a flat side seamed blank made from the blank shown in FIG. 2 and showing the outside surface thereof.

FIG. 4 is a perspective view of the container end closure in tubular form as it appears when first mounted on the mandrel assembly.

FIG. 5 is a perspective view of the container end closure after it has been formed and heat sealed.

FIG. 6 is an enlarged, partial horizontal sectional view, with parts broken away, of the heating structure illustrated in FIG. 1.

FIG. 7 is an enlarged, fragmentary vertical sectional view taken along the line 7-7 in FIG. 6.

FIG. 8 is an enlarged, fragmentary, vertical sectional view taken along the line 8-8 in FIG. 6.

FIG. 9 is a side plane view of one heater side baflle showing the pattern of perforations for directing heated air against selected panels of the container bottom closure.

FIG. 10 is an enlarged perspective view detailing a container in heat receiving position.

FIG. 11 is a perspective view showing a heating station with the heating unit removed.

FIG. 12 is an enlarged perspective view of the heater unit.

FIG. 13 is a plan view detailing a heater unit.

FIG. 14 is a view taken on the line 1414 in FIG. 13.

FIG. 15 is a sectional view taken on the line 1515 in FIG. 13.

FIG. 16 is a sectional view taken on the line 16--16 of FIG. 14.

FIG. 17 is a view taken looking in the direction of arrow 17 of FIG. 14.

FIG. 18 is a view taken looking in the direction of arrow 18 of FIG. 14.

The forming machine generally indicated at 100 in FIG. 1 may be used with any suitable container filling and sealing machine such as the one disclosed in the copending United States patent application of Harry B. Egleston, Ser. No. 448,545, filed Apr. 15, 1965, which application is assigned to the same assignee as the instant application and the disclosure thereof is incorporated by reference herein. The machine 100 is adapted to receive a supply of flat collapsed side seamed blanks from the magazine 101, shown in an empty condition at the left hand side of FIGURE 1. One blank at a time is removed from the magazine 101 and retained in a vertically reciprocating container carrier 120 by suitable means, such as flexible suction cups (not shown). A rotary feeder indicated generally at 102 of the general type disclosed in US Patent 2,936,681, issued May 17, 1960, in the name of James F. Earp is used to transfer the blanks from the magazine 101 to the container carriers 120.

The container carriers 120 rotate with rotary turret assembly 103 in a counterclockwise direction on the machine base 110 about a vertical shaft. Power to rotate the turret 103 is transmitted to the vertical shaft by suitable gears, cams, etc., from a motive source 104. Initially each container bottom closure is heated by the arcuate heating section (FIG. 6) of the present invention by being lowered over an individual heater unit 364 rotating in unison with the turret 103, and retained in its lower position a suitable interval during which time the container bottom closure is selectively heated to a controlled temperature to activate its thermoplastic coating to allow bonding, as disclosed in detail in the aforementioned US. Patent 3,120,335. After the closure is properly heated the carrier 120 transfers the tubular container, indicated at C in FIGURE 1, vertically where it is loaded on its associated vertical mandrel, indicated generally at 105. The mandrels 105 rotate in fixed relation with the container carriers 120 and heating units 364. As the container is being loaded on its individual mandrel by means of the upward movement of the carrier, the continuously rotating turret 103 moves the container C to the position shown in FIGURE 1, where it has completed its upward travel and is approaching the bottom forming assembly 106 disclosed in the copending United States patent application of Harry B. Egleston, Ser. No. 634,633, filed Apr. 28, 1967. While the heating assembly of this application may be used with various types of container forming machines it is disclosed in its embodiment with the forming machine disclosed in copending United States patent application Ser. No. 640,444, filed May 16, 1967, and assigned to the assignee of the instant application. For a detailed description of the operation of the rotating turret assembly 103 shown in FIGURE 1 reference should be made to the last mentioned copending application, the disclosure thereof being incorporated by reference herein.

Referring to FIGURE 2 the container 40 is in flat blank form pressed with a pattern of appropriate score lines and having its inside surface showing. The container is separated into three sections by score lines 41 and 42. The material above score line 41 is the top closure, 2. discussion of which is not necessary for disclosure of the present invention; however, a complete disclosure is given in United States Patent 3,270,940, issued Sept. 6, 1966, on an application of Harry B. Egleston and Charles Z. Monroe. The material between the score lines 41 and 42 is the body group and comprises four panels, 43 through 46, the side seam flap 47. The body group is defined on the sides by edges 48 and 49, and with the panels being separated by score lines 51 through 54. The material below score line 42 is the bottom closure group and comprises major bottom closure panels 55 and 57, fold-in-panels 56 and 58, fold-under panels 63, 64, 67, 68, and flaps 61 and 62, and side seam flap 47. The bottom closure group panels defined on the sides by the edges 48 and 49 are separated by score lines 51 through 54. The major bottom closure panel 55 has the extended tuckin flap 61 and major bottom closure panel 57 has the extended tuck-over flap 62. The bottom fold-in panel 56 is flanked by the triangular fold-under panels 63 and 64 that are connected thereto by score lines 66 and 65, respectively. Similarly, the bottom fold-in panel 58 is flanked by the triangular fold-under panels 67 and 68 that are connected thereto by score lines 72 and 71 respectively.

To form a flat side seam blank, as is presented to the forming machine 20, the panel 46 and side seam flap 47 are folded about score line 53 until their inside surfaces contact the inside surfaces of panel 45 and 44, respectively. The panel 43 is folded about score line 51 until it contacts the inside surface of panel 44 and the outside surface of side seam flap 47. The surface along edge 48, which will meet the outside edge of the side seam flap, will be heated together with the outside surface of side seam flap 47 to activate their thermoplastic coating so that the two surfaces will be bonded when pressed together and cooled. The edge 48 and the score line 54 now appear as one line. The bottom closure portion of flat container blank, as shown in FIGURE 2, now looks like the fragmentary flat side seam container blank as shown in FIGURE 3. It is now ready to be supplied to the forming and filling machine.

When the container 40 is loaded on the mandrel 105, it takes a tubular shape, as seen in FIGURE 4. To form the bottom initially the triangular panels 56 and 58 are moved inward toward each other, after which the major panels 55 and 57 are also moved inward toward each other. This causes fold-under panels 68 to rotate around score line 71 so that the inside surface of panels 68 and 55 are coming together. At the same time panel 68 is rotating about score line 71 the outside surfaces of panels 68 and 58 are approaching each other. Fold-under panels 63, 64 and 67 make the same movements as panel 68 with the panels 55-56, 56-57 and 57-58, respectively. Bottom closure panel 55 moves toward bottom closure panel 57 just enough faster than panel 57 moves toward panel 55 so that tuck-in flap 61 is positioned between foldunder panels 64 and 67, and panels 57, 62. After the bottom closure is completely formed it appears as shown in FIGURE 5.

Turning now to the heating section, as seen in FIG. 6, it comprises an arcuate heater housing generally indicated at 300 cushingly secured upon three vertically movable extending support shafts 304. The shafts 304 extend through aligned openings in the hubs 305 of support base and in the head member 306, secured by bolts 307, and are welded or otherwise secured at their upper end to the mounting ring 308. A spring 310, positioned around each shaft 304 and disposed between the ring 308 and the hub 305, spring load the upper flanges 312 of housing 300, firmly against the lower surface of the manifold plate 166 of the rotating turret housing 164. Sealing or packing members 314 are located in troughs 315 in the flanges 312 to allow for the sealed rotation of manifold 166 relative to the fixed heater housing 300. Suitable insulation 318 is located between the bottom wall of the arcuate housing 300 and the cover plate 320 to insulate the heating unit from the base 110. Coiled compression springs 322 appropriately recessed in the head members 306 also yieldably bias the shafts 304 so that the upward pressure on seals 314 can be adjusted by collar 324 secured to the shaft 304 by a set screw 326. The arcuate ring 308 is fixedly connected by any suitable means to the heater housing bottom wall 328 such as bolt means 330. FIG. 7 shows a sectionthrough the end portion of housing 300 showing radial sealing members 313 retained under pressure by springs 316 which bias movable pins 317, fixedly imbedded in seal 313.

As shown in FIG. 6, the hot air housing 300 includes a first hot air plenum chamber 332 and a second hot air plenum chamber 334 formed in the housing 300 by means of dividing wall 336. Both chambers 332, 334 supply hot air under pressure at a high enough temperature for activating thethermoplastic on a container bottom closure. The hot air is suplied to the chamber 332, 334 through the integral inlet plenum chamber extensions 338, 340 from the burner barrels 342, 344 respectively. The barrels 342, 344 are connected to the distributor 346 by tubes 348. A suitable air suply blower 350 is supported by the frame 352 which is fixed to the base 110 by studs 354 and supplies secondary air under pressure tothe distributor 346. The blower 350 is driven by the motor 356. Primary gas lines 357 are connected to a high pressure gas supply (not shown) for feeding gas to the burners 358, 360. The burners 358, 360 may be of any suitable type and they are adapted to heat the secondary air, which enters through screen 362, and is forced through the distributor 346 by means of the blower 350. The burners should reach a temperature in the range of 700- 800? F. and to obtain this temperature range it may be necessary to adjust the gas and air volumn until the desired operating temperatures are obtained.

As seen in FIG. 1, a heating unit 364 for each of the fifteen working stations is located on the manifold plate 166. The heater units 364 thus rotate with and form a part of the rotary turret 103. As described above, the underside of manifold plate 166 is in spring loaded movable sealing engagement with the hot air housing 300. The manifold plate 166 is provided at each of the work stations with a set of three hot air inlets 366, 368 and 370 as shown in FIG. 11. A distributor plate 372 is removably positioned over each set of inlets by means of a pair of retaining dowels 374 having different diameters such that the small diameter dowel engages notch 376 and the larger diameter dowel receives bore 378. A suitable locking pin may be inserted through pin 374 for positive retention of the plate 372. It will thus be noted that each heating unit 364 is attached only to its associated distributor plate for ready removal for cleaning or replacement.

Each heating unit 364 comprises a center distributor head, generally indicated by the numeral 380, which communicates with the central rectangular manifold opening 366. As best seen in FIGS. 12-18, each distributor head 380 is provided with four generally triangular truncated pyramid shaped upstanding corner members 382 forming upper pyramid chambers 384 which are triangular in cross-section such that each corner chamber 384 communicates with the common lower hot airchamber 386. This unique configuration not only insures uniform distribution of the hot air to each corner chamber 384 but by means of pitched baffie walls 379 directs the hot air outwardly toward the container panels. Another advantage gained over prior art heaters having an overall rectangular box shape is that central V-notch void areas are created which reduce the problem of retaining material in these areas to absorb and radiate heat which will activate the plastic coating of the closure panels in an undesired manner. This in turn allows the container to be placed closer to the distributor head for closer control of the selective heating pattern.

' As best seen in FIG. 12, the upper pyramid chambers 384 are provided with outwardly facing ninety degree oriented, triangularly shaped corner walls. The pair of leading walls 388 each contain a plurality of horizontal hot air discharge slits 390 for selective directing of hot air on the container. It will be noted that the slits 390 in as they approach the edge 73 of tuck-out flap panel 57 (FIG. 18). By contrast the slits 390 in walls 389 culminate in a slit 390" which extends closer to its V-notch portion.

At each of the corner junctures of the walls 388 are vertical slits 391 extending from a point just below the V-notch intersection 377 to a height slightly above the horizontal score 42 which defines the bottom closure portion. The slits 390 and 391 are adapted to be disposed along the inner corners and adjoining surfaces of the bottom closure panels for selective heating of the same when the tubular container is lowered over the central heating head 380. It will be noted in FIG. 17 that the left-hand corner formed by juncture of one each of the pair of walls 381 and 389 is provided with a series of five horizontal slots as opposed to four for each of the remaining three corner junctures. As this corner juncture is located adjacent the lapped side seam fifth panel 47 of the container an increased amount of hot air is required at this location to insure that enough heat is available to penetrate and be absorbed by the double thickness of paperboard material to in turn activate the plastic coating. The central chamber 386 is enclosed by the top wall 392 having bores passing therethrough and a pair of bolts 394 are respectively disposed in the bores and threadably connected to distributor plate 372 to properly position the distributor head 380 relative to the reciprocating carriers 120. The central outlet 366 communicates with the series of holes 395 (FIG. 13) in plate 372 for passage of the hot air to the central chamber 386.

FIG. 8 shows a pair of side bafiie heaters 396 having vertical heater walls 398, parallel to the adjacent heater walls 381, and adapted to be disposed adjacent the outer surfaces of the triangular fold-in panels 56 and 58 together with their respective triangular gusset panels 63, 64 and 67, 68, respectively, for selective heating of the same when the tubular blank is positioned over the heating unit 364. As seen in FIG. 9, the baffle wall 398 of the right hand or outboard side heater is formed with a plurality of hot air discharge ports 400 arranged in a central triangular pattern 401 for heating of the fold-in panel 56, and a pair of triangular patterns 403 for heating fold-under gusset panels 63, 64. The location of the closure panels in relation to the heating pattern is indicated by the dashed lines in FIG. 9. As each pair of bafiie heaters 396 are mirror images of each other only one is described.

It should be particularly noted that the heating pattern of vertical bafile wall 398 is designed so as to provide unperforated areas 405 which form non activated margins on either side of the diagonal score lines 65, and 66. The need to closely control the selective heat pattern here is that the diagonal scores 65, 66 are not pre broken prior to the heating operation as taught by prior art selective bottom heaters of the hot air type, typified by the aforementioned 3,248,841 patent. It can be appreciated that theelimination of the pre-breaking operation in a continuous motion forming machine not only reduces the number of machine operations by virtue of the closure walls retaining their tubular blank shape as shown in FIG. 4, allows for precise selective heating of the critical portions of the closure.

The fact that the panels 56, 63 and 64 and 58, 67 and 68 adjacent the diagonal scores 65, 66 and 71, 72 respectively, are broken and folded through an effective are of and then subjected to pressure during the subsequent forming operation means that the heat activated plastic coating over the raised portion of the diagonal scores (on the inside surface of the container blank) will be subjected to extreme tensile stress. Applicant was faced with the problem of unwanted pin hole type ruptures or tears developing in the stressed plastic coating along the diagonal ribs produced by escaping air and moisture from within the paperboard during the pressure sealing operation. As these folded diagonal score areas are exposed to the liquid product of the container it is essential that the plastic coating thereon remain intact and not develop pin holes which cause wicking or penetration of the liquid into the paperboard and weakening of the closure. It should be noted that the prior art selective heaters avoid the pin hole problem by a pre-breaking operation before heating which reduces the amount of stress applied to these critical areas after they have been activated.

Applicant has devised his heating assembly such that upon vertical lowering of the tubular blank the corner pyramid members 382 serve to guide the panels of the closure over the center distributor 380. In this regard the corner squaring roller 414, attached by means of bracket 416 to the outboard side heater 396 (FIG. 10), acts on a corner of the tubular blank as it is moved down over the center distributor head 380. The blank has a slight inherent diamond shape and the squaring roller applies slight pressure along the edge of the trailing panel 43 of the blank. The roller insures that the critical side foldin panels 56 and 58 are correctly spaced between their respective parallel walls 381 and 398 to prevent activation of the diagonal score areas. In this regard it will be noted that the fact of having the V-notch void area between the corner members 382 results in preventing the diagonal scores from being placed adjacent a radiating source of heat prior to the proper positioning of the blank by means of roller 414. This radiating heat problem is due to the build up and retention of heat by the unit 364 because of the flow of heated air.

It should be noted that applicants unique head design provides for equal distribution of the hot air into the four upper chambers 384. Also the face that each wall 379 is pitched at 60 toward its respective corner of the head baflies the air toward the corner slits for a more effective fiow of air. Another factor in the design over a conventional box shaped head is to a allow cooling at a faster rate to further minimize the heat radiation problem by means of the increased surface area.

As seen in FIGS. 14-18 the distributor head 380 functions to selectively heat the critical inside surfaces of the tubular blank by means of the vertical corner slits 391 and the horizontal slits 390. The fact that applicant utilizes slits or elongated openings in the head 380 in contradistinction to the perforated pattern in walls 398 results from the closer positioning of the blank in relation to the head and localized contact therebetween due to the aforementioned roller means 414 and diamond shaped cross-section of the blank. It will be appreciated that the vertical slits 391, by virtue of extending a distance at least equal to the height of panels 56 and 58, will deliver a substantial amount of hot air to the corner junctures of the closure panels along vertical scores 51-54. However, because these vertical scores have been pre-broken as contrasted with the diagonal scores, the activation of the outer plastic coating will not result in a pin hole condition due to the broken condition of these scores.

It will be noted that an undercut passage 408 is provided in the distributor head 380 to deliver heated air to the deflector or baffle 404 which directs the air onto the outside surface of tuck-in flap 61. The slit 412 (FIG. 18) directs air onto the inner surface of the tuck-over flap 62. As seen in FIG. 14 the horizontal slits 385 in faces 381 extend only a limited uniform distance to avoid the diagonal score area while the long slit 387 insures a proper edge seal between the gusset panels 63, 64, 67 and 68 and the panels 55 and 57. The use of slits in the head 380 has not only reduced fabrication costs, but insures adequate coverage of the inner surface of the closure while redudcing the chance of developing hot or burned spots that occur when port type openings are placed in juxtaposition to the plastic coating.

It should be brought out that the use of slits increase the amount of exposed surface area of the distributor head which allows the dissipation of heat during the nonheating cycle to further reduce heat build-up in the head and avoid excess or unwanted activation of the plastic coating due to heat radiation.

While the invention is susceptible of various modifications and alternative constructions, a certain illustrative embodiment has been shown in the drawings and discussed above in considerable detail. It should be understood, however, that this is no intention to limit the invention to the specific form disclosed but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents fully within the spirit of and scope of the invention as expressed in the appended claims.

What is claimed is:

1. A heating apparatus for use on a container packaging machine for selective heating and activating thermoplastic coated sealing surfaces of tubular contained closure elements having a rectangular cross-section comprising:

(a) a center hot air distributor head formed with rightangle corners and a pair of side heaters each communicating with a housing defining a plenum chamber;

(b) said center distributor and said pair of side heaters each provided with hot air discharge means for discharging the hot air under pressure against the sealing surfaces;

(c) said center distributor having hot air discharge means at each corner thereof comprising a continuous vertical corner slit and a plurality of slits intersecting therewith disposed to selectively discharge hot air in a predetermined interior scored corner juncture of the container closure and,

(d) each said side heater discharge means located on a vertical planar wall and comprising groups of perforations spaced from each other to selectively discharge hot air on a predetermined exterior planar container closure surface wherein the unbroken scores thereon are not subjected to heat activation.

2. The heating apparatus as defined in claim 1, wherein:

(a) said center distributor is provided with a lower hot air chamber and four uppercorner chambers each communicating with said lower chamber wherein hot air is distributed substantially equally to each said corner discharge means.

3. The heating apparatus as defined in claim 2, where- (a) each said upper corner chamber has a triangular pyramid configuration.

4. The heating apparatus as defined in claim 3, wherein:

(a) each said corner pyramid is formed by two equal substantially right-triangular corner faces opposed respectively to adjacent inner surfaces of the container closure elements and a third triangular face, and

(b) said third triangular face being inclined toward its associated corner discharge means to bafiie the hot air thereto.

5. The heating apparatus as defined in claim 1, wherein:

(a) each said vertical corner slit extends a distance at least equal to the height of the corner juncture of the container closure elements.

6. The heating apparatus as defined in claim 1, wherein:

(a) said plurality of slits intersecting with their associated vertical slit are horizontally oriented; and

(b) said plurality of horizontal slits in opposed relation to certain of the closure elements extending progressively greater in length to selectively heat the closure elements.

7. The heating apparatus as defined in claim 1, wherein:

(a) said plurality of slits intersecting with their associated vertical slit are horizontally oriented; and

(b) said plurality of horizontal slits adjacent to the closure elements having unbroken scores thereon extending equally a predetermined amount to selectively heat only the adjacent corner area.

8. The heating apparatus as defined in claim 2, wherein:

(a) one face of said lower hot air chamber is provided with first hot air discharge means for selectively discharging the hot air under pressure directly against the inner surface of a tuck-out flap portion on one of the closure elements; and

(b) an opposed face of said lower hot air chamber is provided with second hot air discharge means positioned at a lower level than said first discharge means for discharging the hot air under pressure beneath a corresponding closure tuck-in flap portion and against a bafile means whereby the air is selectively directed on the outer surface of the tuckin flap.

9. The heating apparatus as defined in claim 1, wherein:

(a) guide means are provided on said apparatus to apply pressure to a predetermined edge of the tubular container to square the container about said center distributor. 10. The heating apparatus as defined in claim 4, where- (a) the angle of inclination of said third triangular face is substantially 60 degrees.

References Cited UNITED STATES PATENTS FREDERICK L. MATTESON, IR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner. 

